Rim-Driven Hydroelectric Unit for Lower Thrust Bearing Loads
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Solution Overview
Problem
Offshore hydroelectric energy storage plants face challenges with maintenance and replacement of components, particularly thrust bearings, which lead to machine downtime and high maintenance costs.
Innovation Solution
A hydroelectric unit comprising a rim-driven hydraulic machine with an impeller having at least two blades, coupled with a motor/generator featuring an annular rotor and stator, designed to minimize axial loads on thrust bearings through optimized magnetic flux configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional hydroelectric units with shaft-driven turbines are used offshore, then energy storage function is achieved, but thrust bearing maintenance frequency increases and reliability decreases
Solution Approach 1:
The patent extracts and eliminates the thrust bearing component from the hydroelectric unit by transitioning from a shaft-driven turbine to a rim-driven turbine configuration. The rim-driven design allows the turbine runner to be directly coupled to the generator rotor at the rim, removing the need for a central shaft and thrust bearings, thereby eliminating maintenance issues associated with these components in offshore environments
Solution Approach 2:
The patent replaces the traditional mechanical shaft-driven turbine system with a rim-driven turbine system that directly couples the turbine runner to the generator rotor. This substitution eliminates the mechanical shaft and thrust bearing components, reducing moving parts and maintenance requirements while improving reliability for offshore energy storage applications
2Ease of repair
If rim-driven hydraulic machines are used, then thrust bearing wear is reduced, but device complexity increases due to annular rotor and stator configuration
Solution Approach 1:
The rim-driven turbine runner serves multiple functions: it acts as both the hydraulic turbine component that converts water flow energy to mechanical rotation and as the rotor assembly for the generator. This multi-functionality integrates the turbine and generator components, reducing the number of separate parts while maintaining the necessary complexity for efficient energy conversion
Solution Approach 2:
The patent employs a nested configuration where the annular rotor is positioned within the annular stator, creating a compact motor/generator assembly. The turbine runner is coupled to the rotor, nesting the hydraulic and electrical components together in a space-efficient arrangement that manages device complexity through compact integration
3Reliability
If maintenance and replacement of components is performed frequently, then reliability is maintained, but machine downtime increases and maintenance costs rise
Solution Approach 1:
The rim-driven hydraulic machine design is inherently more reliable with fewer moving parts, particularly eliminating thrust bearings that require frequent maintenance. The system essentially serves itself by reducing the need for external maintenance interventions, as the direct-coupled turbine and generator have fewer components that can fail or require replacement in offshore environments
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution reduces the axial thrust on thrust bearings, leading to lower wear rates and extended maintenance intervals, thus reducing downtime and maintenance costs while maintaining reliable operation.
Implementation Method 1
a motor/generator configured to selectively supply mechanical energy to the impeller or convert mechanical energy produced by the impeller into electricity
Implementation Method 2
designed to minimize axial loads on thrust bearings through optimized magnetic flux configuration
Data Source
AI summary
An hydroelectric unit extends along a longitudinal axis and includes a least one rim-driven hydraulic machine comprising an impeller provided with at least two blades, and at least one motor/generator configured to selectively supply mechanical energy to the impeller or convert mechanical energy produced by the impeller into electricity. The motor/generator includes an annular rotor arranged about the impeller and an annular stator arranged, at a distance, about the annular rotor; the annular rotor being coupled to the impeller and including a plurality of rotor poles, which are distributed along an annular surface, are arranged parallel one to another and extend transversal to a plane containing the longitudinal axis forming a first angle with the plane containing the longitudinal axis. The annular stator includes a plurality of stator windings and a plurality of stator slots configured to guide the magnetic flux and to house respective stator windings. The stator slots are arranged parallel one to another and extend transversal to a plane containing the longitudinal axis forming a second angle with the plane containing the longitudinal axis.